Technical Field
The present disclosure relates to a vehicle collision detection system.
Related Art
Japanese Patent Application Laid-Open (JP-A) No. 2001-030871 describes technology for an occupant protection device provided with left and right satellite sensors at a front section of a vehicle. The satellite sensors are configured to detect a vehicle collision by detecting backward movement of a headlight lamp body. In JP-A No. 2001-030871, a threshold used to compare detection results of a floor sensor is modified on the basis of ON signals from the left and right satellite sensors, and an airbag device is actuated based on the result of comparing detection results of the floor sensor against the modified threshold. JP-A No. 2001-030871 states that an advantageous effect of this technology is the ability to detect collisions even in cases in which a collision counterpart object is comparatively soft, or in cases in which the collision mode is an underride mode.
An underride collision mode collision arises in cases in which, for example, a comparatively small vehicle (such as a passenger car) collides with the rear of a comparatively large vehicle that has a space below a vehicle rear section (for example, a large truck with a space below the trailer bed). Moreover, an underride mode is a collision mode in which the front section of the comparatively small vehicle at the rear burrows into the space below the rear section of the comparatively large vehicle in front. Moreover, in an underride collision mode, there is a tendency for acceleration detected by satellite sensors to be similar to that detected in a general collision that is not in the underride collision mode, while the acceleration detected by the floor sensor is markedly smaller than in a general collision.
However, when a vehicle collides with a comparatively light object such as a small animal, the acceleration detected by the satellite sensors and the acceleration detected by the floor sensor sometimes exhibit a pattern of change similar to that in an underride collision. The technology described in JP-A No. 2001-030871 is thus unable to make a clear distinction between underride collision mode collisions and collisions between the vehicle and a comparatively light object. Accordingly, there is room for improvement in the technology described in JP-A No. 2001-030871 since there is a possibility that an occupant restraint device such as an airbag device might actuate at a timing when occupant restraint is not required.